Automatic adjusted light switching circuit

ABSTRACT

In this invention, an automatic adjusted light switching circuit which can feed an illuminating light to an endoscope is provided with a light source emitting an illuminating light to illuminate an object. The illuminating light has the light amount controlled by an iris driving circuit. An adjusted light controlling circuit for a still camera outputs a control signal controlling the iris driving circuit with a photometric signal. An adjusted light controlling circuit for a video camera outputs to the iris driving circuit a control signal for making a video signal of the most suitable brightness from a video signal obtained from a solid state imaging device imaging the object image. Either one of the control signals output by the adjusted light controlling circuit for the still camera and the adjusted light controlling circuit for the video camera is slected by a switching circuit and is input into the iris driving circuit.

FIELD OF THE INVENTION

This invention relates to an endoscope light source apparatus which canfeed the most suitable illuminating light in photographing andtelevision imaging.

BACKGROUND OF THE INVENTION

An electron type endoscope (which shall be briefly mentioned as anelectronic endoscope or electronic scope) wherein such solid stateimaging device as a charge coupled device (abbreviated as CCD) is usedinstead of an image guide transmitting optical images is recentlypracticed so that an imaged endoscope picture image may be displayed ona TV monitor.

Also, a photographing camera (which shall be briefly mentioned as astill camera) is fitted to an eyepiece part of an optical endoscope(which shall be briefly mentioned as a fiber scope) wherein aconventional image guide is used so as to take a photograph or a TVcamera containing such imaging means as a solid state imaging device isfitted to the same part so as to display a picture image on a TVmonitor.

Now, the above mentioned electronic scope or fiber scope is used asconnected to a light source apparatus feeding an illuminating light.

Conventionally, such light source apparatus is made in advance to beconnected with a fiber scope so that, when a still camera is connectedto the fiber scope, an iris will act so that the film surfaceilluminating degree may be constant and an automatic light adjustmentwill act. Therefore, even if the observing position varies, by theaction of this automatic light adjustment, an object to be observed willbe able to be observed by the observer always at a constant brightness.Further, the automatic light adjusting circuit is so designed that theresponsiveness will be optimum when a still camera is connected.

However, it is in more cases that a TV camera is connected to a fiberscope and a picture image is observed on a TV monitor. For the lightadjustment in such case, a video signal from the TV camera is input asan automatic light adjusting signal into the above mentioned automaticlight adjusting circuit. However, this automatic light adjusting circuitcorresponds to the still camera as mentioned above, therefore can not hesaid to be most suitable particularly in the responsiveness, forexample, a hatching (the response is too early to be stable andflutters) and response delay (the response is too late to follow thevariation of the brightness of the object) have occurred and suchdisadvantage that the observer is not only fatigued in the eye but alsocan not make a sufficient diagnosis has occurred. Further, in case anelectronic scope is connected to one light source apparatus, the videosignal from the electronic scope will be of the same kind as of the TVcamera and, when it is connected to the automatic light adjustingcircuit for the fiber scope, the same disadvantage as is mentioned abovewill occur.

OBJECT AND SUMMARY OF THE INVENTION

The present invention is made in view of the above mentionedcircumstances and has it as an object to provide an endoscope lightsource apparatus whereby, even in case a photograph is taken with astill camera fitted to a fiber scope, even in case a monitor observationis made with a TV camera fitted to a fiber scope and even in case amonitor observation is made with an electronic scope, the most suitableresponsiveness and light amount can be obtained and a clear photographand an observed picture image easy to observe can be obtained.

The automatic adjusted light switching circuit of the present inventionis provided with a video adjusted light controlling circuit and a stilladjusted light controlling circuit outputting respectively a videocontrolling signal and still controlling signal which can adjust aniris. Either one of the these two controlling signals is selected by aswitching circuit to be input into an iris driving circuit which drivesthe iris and controls the light amount.

The other features and advantages of the invention will become apparentenough with the following explanation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 3 relate to the first embodiment of the present invention.

FIG. 1 is a block diagram explaining the formation of an entireendoscope apparatus.

FIG. 2 is a block diagram explaining the operation of a track switchingcircuit.

FIG. 3 is a circuit diagram of an endoscope light source apparatus.

FIG. 4 relates to the second embodiment of the present invention and isa circuit diagram of an endoscope light source apparatus.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The embodiments of the present invention shall be explained in thefollowing with reference to the drawings.

FIGS. 1 and 2 relate to the first embodiment of the present invention.FIG. 1 is an explanatory view of the formation of an entire endoscopeapparatus. FIG. 2 is a circuit diagram of an endoscope light sourceapparatus.

In FIG. 1, an endoscope light source apparatus 1 can be connected to afiber scope 2 removably fitted with an externally fitted still camera 5and to a control apparatus 4 processing the signal of the output of anexternally fitted TV camera 3. The control apparatus is to display anobject image on a TV monitor 6.

The above mentioned fiber scope 2 has an elongate insertable part 7 andan operating part 8 connected to the rear end side of this insertablepart 7. A universal cord 9 is extended from this operating part 8 and isprovided at the tip with a light source connector 11. Further, an eyepiece part 10 is provided at the rear end of the operating part 8.

A light guide 12 formed of a fiber bundle transmitting an illuminatinglight is inserted through the above mentioned insertable part 7. Theilluminating light emitted from a light source part 13 within the abovementioned light source apparatus 1 is fed to the entrance end surface ofthis light guide 12, is transmitted to the exit end surface side and isprojected out of this exit end surface to be able to illuminate theobject side in the front.

An image forming objective lens 14 is arranged in the tip part of theabove mentioned insertable part 7 so that the entrance end surface of animage guide 16 formed of a fiber bundle inserted together with the abovementioned light guide 12 through the insertable part 7 may be present inthe image forming position of this objective lens 14. An eyepiece lens17 is arranged as opposed to the exit end surface of this image guide 16so that the observer can make a naked eye observation with this eyepiecelens 17 from the eyepiece part 10 fitted with the above mentionedexternally fitted still camera 5. Within this externally fitted stillcamera 5, an image forming lens 18 and a beam splitter 19 in the rear ofthis imaging lens 18 are provided so that the optical axis may coincidewith that of the above mentioned objective lens 17. A film 21 isarranged in the image forming position of this beam splitter 19 so as toreceive the light transmitted through the beam splitter 19. A shutter 20is interposed between this beam splitter 19 and the film 21 so as to beable to intercept the transmitted light. The reflected light by the beamsplitter 19 enters such light receiving device 22 as, for example, aphotodiode. The light entering this light receiving device 22 isphotoelectrically converted and is input as a voltage signal into alightmeasuring circuit or photometer 23. From the photometer 23, the voltagesignal is input as alight amount information signal into a still cameraadjusted light controlling circuit 28 provided within the light sourceapparatus 1 through a terminal 24 provided in the eyepiece part 10, atransmitting line 26 inserted through the operating part 8 and universalcord 9 and a contact 27 provided in alight source connector 11.

On the other hand, within the externally fitted TV camera 3 which can beremovably provided in the eyepiece part 10 of the fiber scope 2, animage forming lens 29 is provided so that the optical axis may coincidewith that of the eyepiece lens 17 in case the TV camera 3 is fitted tothe fiber scope 2. A solid state imaging device 31 is provided in theimage forming position of this image forming lens 29 so as to form anobject image entering through the image guide 16. The object image isphotoelectrically converted by this solid state imaging device 31 and isinput as an electric signal into a video signal processing circuit 32within the above mentioned control apparatus 4. The input electricsignal is processed by the video signal processing circuit 32 and isoutput as a composite video signal to the TV monitor 6 and the objectimage is displayed on the picture surface.

The composite video signal output from the above mentioned video signalprocessing circuit 32 is input into a video adjusted light controllingcircuit 33 provided within the light source apparatus 1 through acontact 35a provided in a connector 35.

In the above mentioned still camera adjusted light controlling circuit28 and video adjusted light controlling circuit 33, information signalsrelating to the light amounts and responses most suitable to theexternally fitted still camera 5 and externally fitted TV camera 3 areproduced and are input into an iris driving circuit 36 through aswitching switch 34. This switching switch 34 is switched by a switchingcircuit 37 discriminating whether the endoscope connected tot he lightsource apparatus 1 is a fiber scope 2 or electronic scope or whether thecamera fitted tot he fiber scope 2 is a still camera 5 or TV camera 3 sothat, in case either of the electronic scope and externally fitted TVcamera is used, the control signal of the video adjusted lightcontrolling circuit 33 will be input into the iris driving circuit 36and, in case the externally fitted still camera 5 is used, the controlsignal of the still camera adjusted light controlling circuit 28 will beinput into the iris driving circuit 36.

FIG. 2 shows a concrete block diagram of the switching circuit 37.

In FIG. 2(a), when the connector 35 of the control apparatus 4 isconnected to the light source apparatus 1, a pin 80 provided on the endsurface of the connector 35 will switch on a switch 81 provided in thelight source apparatus 1 to excite a coil 82 forming the switchingswitch 34 which will be switched to the video adjusted light controllingcircuit 33 side and a control signal will be delivered to the irisdriving circuit 36. As in FIG. 2(b), in case the light source connector11 of the fiber scope 2 is connected to the light source apparatus 1, asthe connector 11 is not provided with the pin 80, the switch 81 will notbe on and the coil 82 will not be excited. In case this switching switch34 is not excited, it will be switched to the still camera adjustedlight controlling circuit 28 and the control signal output from thestill camera adjusted light controlling circuit 28 will be delivered tothe iris driving circuit 36.

By the way, a manual switch may replace the switching circuit 37.

A condenser lens 39 and iris 41 re arranged on the light path connectingthe entrance end surface of the light guide 12 of the above mentionedlight source part 13 and the light source lamp 38. This iris 41 isdriven by the control signal of the above mentioned iris driving circuit36 so that the illuminating light emitted from the light source lamp 38may be controlled to have the most suitable light amount andresponsiveness.

In FIG. 3, the formation of the still camera adjusted light controllingcircuit 28, video adjusted light controlling circuit 33 and iris drivingcircuit 36 shall be concretely explained.

The composite video signal processed by the video signal processingcircuit 32 is input into the video adjusted light controlling circuit33. This input signal is compared with a reference potential 42 by acomparator 43. Further, the responding speed is determined by aresistance R1 and condenser C1. The signal after the comparison anddetermination is input by the switching switch 34 into a comparator 44within the iris driving circuit 36. The output of this comparator 44 isinput into a driving coil 46 of an iris 41 through an output circuit 45to drive the iris 41 provided with a braking coil 47. A braking signalis generated from this braking coil 47. The comparator 44 can stablydrive the iris 41 with the difference between this braking signal andthe input signal from the video adjusted light controlling circuit 33.On the other hand, in the case of using the still camera, thephotometric signal from the photometer 23 is input into the still cameraadjusted light controlling circuit 28. the input signal is compared witha reference potential 48 by a comparator 39 and further the respondingspeed is determined by a resistance R2 and condenser C2. The signalafter the comparison and determination is input by the switching switch34 into the comparator 44 within the iris driving circuit 36. The outputof this comparator 44 is input into the driving coil 46 of the iris 41through the output circuit 45 to drive the iris 41. By the way, the iris41 is provided with the braking coil 47. A braking signal is generatedfrom this braking coil 47. The comparator 44 can stably drive this iris41 with the difference between this braking signal and the input signalfrom the video adjusted light controlling circuit 33.

In this case, the condenser C1 and resistance R1 are set at the timeconstant and gain most suitable to the externally fitted TV camera 3 andthe condenser C2 and resistance R2 are set at the value most suitable tothe photometric signal from the externally fitted still camera 5. Thereference potentials 42 and 48 are set respectively for the externallyfitted TV camera 3 and still camera 5 so that the illuminating light maybe of the most suitable brightness.

By the above mentioned formation, even in case the externally fittedstill camera 5 or TV camera 3 is fitted, the most suitable light amountand responsiveness can be omitted.

The reference potentials 42 and 48 may be made variable or a pluralityof them may be provided to vary the light amount so that the brightnessmay be adjusted to be as desired by the user. Further, the abovementioned operation may be made by an instruction from a microcomputer.In such case, the brightness desired by the user may be memorized in themicrocomputer.

FIG. 4 shows the second embodiment of the present invention.

In this embodiment, the adjusted light controlling circuit of the firstembodiment is used for both of the externally fitted still camera 5 andTV camera 3.

The video signal from the externally fitted TV camera 3 and thephotometric signal from the externally fitted still camera are selectedby a switching switch 51 and the video signal is input into a comparator52 within an adjusted light controlling circuit 50. A referencepotential 53 corresponding to the most suitable light amount of theexternally fitted TV camera 3 and a reference potential 54 correspondingto the most suitable light amount of the externally fitted still camera5 are selected by a switching switch 56. The selected referencepotential 53 and the video signal are compared by the operator. Thiscomparator 52 is connected with the condenser C1 and resistance R1determining the responding speed most suitable to the externally fittedTV camera 3 and the condenser C2 and resistance R2 determining theresponding speed most suitable tot he externally fitted still camera 5through switching switches 57 and 58 by which the condenser C1 andresistance R1 are selected so that information signals of the lightamount and responding speed most suitable to the externally fitted TVcamera 3 may be input into the iris driving circuit 36 from thecomparator 52.

By the way, the switching switches 51, 56 and 58 are controlled by theswitching circuit.

In this embodiment, as compared with the first embodiment, the number ofthe costly comparators can be reduced and therefore the cost can bereduced.

The other formations, operations and effects are the same as in thefirst embodiment.

In the above mentioned respective embodiments the fiber scope fittedwith the externally fitted TV camera or still camera has been describedbut an electronic scope may be connected instead of the externallyfitted TV camera.

As explained above, according to the present invention, even in the caseof photographing with a still camera fitted to a fiber scope, ofmonitor-observing with a TV camera, fitted to a fiber scope or ofmonitor-observing with an electronic scope, the optimum responsivenessand light amount can be obtained and a clear photograph and an observedpicture image easy to observe can be obtained.

In this invention, it is apparent that working modes different in a widerange can be formed on the basis of this invention without departingfrom the spirit and scope of the invention. This inventions is notrestricted by its specific working mode except being limited by theappended claims.

What is claimed is:
 1. An automatic adjusted light switching circuitcomprising:a light source emitting an illuminating light to illuminatean object; a light amount controlling means capable of controlling thelight amount of said light source; a first light adjusting means capableof outputting a control signal which can adjust said light amountcontrolling means with an information signal relating to the brightnessof said object; a second light adjusting means capable of outputting acontrol signal having a light adjusting characteristic different fromthat of the first light adjusting means from a video signal obtainedfrom a solid state imaging device by imaging said object image with saidsolid state imaging device; and a selecting means capable of selectingthe control signals output from said first light adjusting means andsecond light adjusting means and of inputting into said light amountcontrolling means the control signal output from either one.
 2. Anautomatic adjusted light switching circuit according to claim 1 whereinsaid first light adjusting means is a still camera light adjusting meanscapable of outputting a control signal by inputting a photometric signalincluding an information relating to the illumination intensity of theobject image formed on a photographic film fitted to the still camera.3. An automatic adjusted light switching circuit according to claim 1wherein said second light adjusting means is a video light adjustingmeans capable of outputting a control signal which can adjust the lightamount of said light source to make the brightness most suitable to theinput video signal.
 4. An automatic adjusted light switching circuitaccording to claim 2 wherein said still camera light adjusting means hasa comparator comparing the reference potential and photometric signal.5. An automatic adjusted light switching circuit according to claim 3wherein said video light adjusting means has a comparator comparing thereference potential and video signal.
 6. An automatic adjusted lightswitching circuit according to claim 1 wherein said first lightadjusting means and second light adjusting means are integral, areformed of the same comparator and selectively perform the functions asof said first light adjusting means and second light adjusting means byselecting a plurality of electric parts connected to said comparator.